Art of producing electrical precipitation, etc



Jan 2, 1923. 1,440,886

A. Fv NESBIT. ART OF PRODUCING ELECTRICAL PRECIPITATION, ETc.

FILED SEPT. 7. 1916. 4 SHEETS-[SHEET I Fla-L FIE-E- FIE E III-III- %J2Z%7M M f Jan. 2, 1923. 1,44@,886

A. F'. NESBIT. ART OF PRODUCING ELECTRICAL PRECIPITATION, ETC.

FILED SEPT. 7. 1916. 4 SHEETS'SHEET 3 FI-, v G (i: 5- rig-v INVENTOR Jan. 2, 19.23.

A. F. NESBIT. ART OF PRODUCING ELECTRICAL PRECIP] TATION, ETc.

4 SHEETS-SHEET 4 Fl LED SEPT. 7. 1916'.

FHGJJn.

INVENTOFI Patented .llen. 2, 1923 S TE ARTHUR IE. NESBI'I', OF 'WELIKINSBURG, PENNSYLVANIA.

ART OF PRODUCING ELECTRICAL PRECIPITATION, ETC.

application filed September 7, 1916. Serial No. 118,899.

T all whom it may concern:

Be it known that I, ARTHU F. NESBIT, a citizen of the United States, residing at VVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in the Art of Producing Electrical Precipitation, etc., of which the following is a. specification.

My invention relates to the art of separating solid and liquid particles from gaseous or fluid streams by electrical precipitation.

Separation of particles from streams of these types by subjecting the streams to the action of opposing electrode systems has been heretofore proposed and apparatus for such purpose has been placed in service to a limited extent. Various ways of meeting service conditions have been suggested, but the difficulties incident to the particular uses of apparatus of this type have been such as to generally provide unsatisfactory results.

The early developments of the art provided for the formation of fields based on the point discharge theory of operation, as by the use of barbed wire, filamentous material, wire mesh, and electrodes with serrated edges as the discharge electrodes. While these structures provided separating fields, the fields were of a type in which the discharge is normally localized, a structure inherently lending itself to the ready formation of disruptive discharges through the fact that the localization efiect is present at 35 all times and requires but a slight change in conditions to reach a point Where breakdown of the stream occurs resulting in the formation of the disruptive discharge.

1 During these developments the idea of 40 employing spaced-apart, opposing flat plates as electrodes was used, but the efiiciency, ex-

' cepting under especially favorable conditions, was comparatively small due to the general inability to concentrate the discharges.

Later developments indicated the superiority oil the corona type of discharge, such as is provided by the use of wires located in tubes, each wire extending-axially through a tube and forming therewith a unit adapted to provide separating action bypassing the stream through the tube, the Wire and tube forming theopposing electrodes, the surfaces of the electrodes having a concentric relation one to the other and providing a uniform field surrounding the discharge electrode.

As a result of a number of tests, experimental and otherwise, I found that, although the formation of symmetrical fields by the tube and wirestructure provides for serviceability, more efiicient results can be obtained. by partially or wholly concentrating the stra n lines of the field thereby increasing the ionizing efi'ect of the field. For instance, I have located the wire electrode with its axis out of the symmetrical axis of the tube electrode, thus tending to concentrate the strain lines on that face of the wire electrode closest to the surfaceof the tube. In another forin, I have produced a somewhat similar result by making the surface opposmg the wire electrode of a larger radius than thatof the surface of the wire, and have extended this idea to a point Where such opposing surface is substantially fiat So that the non-concentric relation between the surface of the two electrodes tended to produce ionization zones. One development of the latter idea is to provide a plurality of such 30 zones in the direction of travel of a stream through the ionization field. As will be understood, the inner or discharge electrodes in these cases are a wire with the usual circular cross sectional contour. As better re- 35 'sults are obtainable with wires of smaller diameter, due to greater concentration of strain lines atthe surface, the application of the discoveries indicated above is limited to such use as would not damage the wire. I also found that this use may be amplified to a certain extent by the substitution of a metallic bar for the wire, such bar'having anedge to produce the concentration, this edge extending in the direction of length of the bar, but while this construction added strength to the electrode and thereby provided additional stability to the apparatus as a whole, its application is limited to uses Where conditions would not materially affect 0 the integrity of the bar or, its support, as for instance, conditions where tendency of expansion and contraction of the bar under varying temperatures of gases would not be present to material extent. This limitation 5 is due to the fact that the efiicient' operation of such apparatus is dependent to a great extent on mainta ining the discharge between gases in blast or other furnace work, cement manufacture, etc., expansion and contraction of the bar may so affect the bar as to greatly decrease such efficiency.

As-the result of further experiments and tests, I have found that the general idea of this concentration of active surfaces of opposed electrodes can be obtained in various other ways. F or'instance, by the use of a bar of considerable cross-sectional'area, the bar itself having its contour angular in cross section,.th e apices of the angles forming edges which are at least equally as effective in concentrating the strain lines as are the curved surfaces of the wire electrodes. I also found that by subjecting the bar to a twisting action, each edge would form one or morespirals in the direction of length of the bar, thus providing a plurality of .spiral discharge zones when located within a tubular electrode, the zones being continuous if the tubular electrode is circular in cross section, or interrupted if of noncircular configuration.

During my experiments,'it was found that a twisted bar of this form, under expansion action, tended to elongate by slightly untwisting, so that while the untwisting action might slightly affect the spiral, such'result would not materially affect the distance'between the edge and the opposedelectrode surface. Hence, by firmly suspending the bar electrode at its upper end,.it could be employed in connection with. installations where gases of high temperatures were en- V effective destruction of theelectrodes, but.

countered, the elongation of the electrode ndt materially affecting the radial length of thegap between electrodes, so that variationsisin temperatures of the gases would .not affect operation, thus enabling the bar structuregjto be usable under conditions short of actual destruction of the-bar by high temperatures.

.Not only does this discovery provide for meeting conditions. with respect to nonin addition provides an electrode structure in which it ispossible to control toa cer I tain extent the operations of the apparatus.

This is due to the fact that the twisting of the bar causes its edges to form spiral zones in the direction of length of the ionization 6'5 field without the formation of objectionable pockets; as there is a tendency of the gases to attempt to dodge these zones, the gases 'will tend to take a s iral course through the field, thereby ten mg to set up a centrifugal action within the gases. As will be obvious, however, the amount of deflection of the gases spirally will depend to a great extent upon the velocity of the gases passing through the field, a more rapid velocity decreasing the defiection from a strai ht course and thus causingthe gas to be su jected to the action of an increasing number of zones; since the normal action of the apparatus is designed to cause thepath of travel of the gases to intersect-to a more or less degree-the direction of length of the zones, it will be clear that change in velocity would tend to vary the angularity of such intersection.

Such formation tends to produce the efiect of a threaded electrode, the edges extending spirally in the direction of length of the collecting electrode similar to the threads of a threaded bar; where the structure is produced by machining instead of .by twist; ing, a finer'pitch may be pr oduced.

ditions are favorable, satisfactory results can be obtained by breaking the continuity of the spiral zones, as, for instance, by varying the contour of the outer electrode to vary the distance between the two electrode surfaces. effect can be produced bysubstitutingan annular ridge for the spiral thread arrange ment. thus shifting the direction of length of have also discovered that where con-.

' I have further found that this the thread from that of a spiralto that heat ed on a single cross-sectional plane of the discharge electrode. 'By'such arrangement,

the zones are located on planes extendingv at direct right angles to the. axis of the electrodes, "causing the gaseous" or fluid stream to intersect the zones at such direct right angle. Consequently, in such form, the outer electrode may be concentric with the discharge edge, producing a continuous circular zone, the ridges being spaced apart in the'direction of length of the electrodes 'to. provide the interruption effect.

Inproviding this result, especially under high temperature conditions, I preferably form the discharge electrode of separate units, each carrying a ridge, the units being axially aligned. This not only permits of simplicity in manufacture with an assurance of simllarity ln'umt configuratlon, but also enables any desired spacing of zones'to meet operating conditions, as well as permitting the use of any desired number of zones. In addition,the unit structure provides for unit expansion and; contraction andpermits manufacture in a manner to practically .pre-

vent any material change in the distance between opposing electrodes under expansion and contraction.

To these. and other ends, the nature of which will be readily understood as the invention is hereinafter disclosed, said invention consists in the methods and structures hereinafter fully described, illustrated in the accompanying drawings, and more particularly pointed .out in the appended claims.

In the accompanying drawings, in which similar reference characters indicate similar parts in each of the views,

Fig. 1 is a diagrammatic sectional view illustrating one way of concentrating electric lines of force.

Fig. 2 is a similar view showing the use of parallel electrodes arranged to concentrate the electric lines of force in zones.

Fig. 3 is a diagrammatic cross section of opposing electrode systems adapted to .produce ionization zones with electric lines of force.

Fig. 4 is a view similar to Fig. 3 but showing the discharge electrode as having been subjected to a torsional twisting action.

Fig. 5 is a diagrammatic view showing a simple arrangement of apparatus for pro-' viding the electric the ionization field. Figs. 6-10 inclusive are diagrammatic cross sectional views showing various Ways in wlhich the present invention may be develo e Fig. 11 is a diagrammatic sectional view showing a different form in which the invention may be applied.

Fig. 12 is a detail view, partly in section pressure for producing and partly in elevation, showing a modified arrangement of discharge electrode.

As heretofore referred to, in developing the art of separation-by the use of ionization fields, the concentration of the strain lines was found to provide greater efficiency than where the field was made uniform by locating the axis of the discharge electrode on the symmetrical axis of the opposing tube electrode with the surfaces of the two electrodes concentric with each other. This increase of efiiciency is due to the fact that the strain lines are concentrated instead of diffused, thereby providing a zone of increased ionization effect.

. As is well known, whentwo flat metallic plates are separated by a pane of glass of similar dielectric having a thickness approximately one-eighth inch, and a difference ofelectric pressure is maintained between these plates (acting as electrodes) it is difiicult to discover any electric action as taking place between the two plates until an effective pressure of six or seven thousand .volts is applied. The first visible evidence of such electrical action is in the, form of a pale violet light termed the corona at the edges of the plates or electrodes. By increasing the difference of electrical pressure, the

corona brightens and broadens out and mayconcentrating be accompanied by thin and brilliant streamers emanating from the electrodes and darting in all directions over the surface of the glass.

. When, however, the discharge electrode is in the form of a fine wire, as in Fi 1 the axis of the. wire being plate and the opposite discharge takes place at the lower part of the surface of the wire only, the strain lines being concentrated and increasing the ionization effect. When the dielectric flux density attains a value that will rupture the dielectric, the latter gives way at this parparallel to the glass electrode, the corona ticular region, and the dielectric flux is rewire, passing through the glass plate 0 in accordance with the well known laws of refraction of electric lines of force and terminate upon the upper surface of the plate C.

In Fig. 2, a pair of wires are shown, illustrating the zonal effect produced when the discharge electrode is in the form of a pair of wires arranged parallel to each other and to the opposing electrode.

As will be understood, this concentration effect is due to the fact that the opposing surfaces of the electrodes have a non-concentric relation. Obviously, the concentrating effect becomes more apparent as the diameter of the wire decreases. While this concentration efi'ect increases with the decrease in the diameter of the wire, however, stability of the structure decreases in correspondence; in view of the fact that con1- .mercial use of such apparatus must be accompanied by stability, the efiiciency produced by the concentration is limited by the size of wire capable of providing the desired stability.

As heretofore referred to, this limitation may be eliminated by the use of a bar formed of comparatively high temperatures, expanquently,

cannot well be extended to installations where temperature conditions of the gases or other medium may affect the integrity of I the structure.

As heretofore pointed out, developments as a result of further experiments and tests" have shown that it is possible to employ this idea of strain line concentration and nonconcentric relation between the opposing electrode surfaces where the outer electrode is tubular and without the'limitations provided.by the use of wire as the discharge electrode, this result being obtained, mom form, by the use of a bar having its axis on the symmetrical axis of the tube, but having its cross sectional contour angular, thus .providing a plurality of parallel edges extending in the direction of length of the tube, each edge acting to concentrate the electric lines of force or strain lines, as indicated more particularly in Fig. 3, in which the outerelectrode is shown in the form'of'a tube 6, and the discharge electrode as inthe .form of a bar a of considerable area incross duced in any suitable. manner, as by'mac section and having its cross sectional contour in the'form of a square, thus forming four parallel spaced-apart zones extending from one end to the other of the field.

' Inasmuch, however, as the gases would travel in the directionof length of the zones, such structure would be somewhat ineffective by reason of the fact that the tendency of .the stream wouldbe to dodge the zones and pass through the free spaces between zones.

To overcome this objection, and yet maintain the increased stability rovided by a bar of the character mentione I preferably form the bar in such manner as to cause each edge to form a spiral extending around the bar. This spiral arrangement may be ro- Z 1ning a bar of proper cross section to form the spiral. However, I prefer to produce this result by a twisting action on the bar itself,

thus not only producing the spiral efiectin a simple manner, but in addition, tending to slightly'cha'nge the cross sectional contour of-the bar by slightly coneaving its sides between the edges, see Fig. 4, with the result that the angle at the sides forming the edge is decreased from the initial form, thus increasing the concentrat-' in' eifect. 1

his twisting action does not affect the formation of spaces between the edges or between thezones 2111130111125 adjacent the discharge edges, the twisting action simply shifting these spaces into spiral form. As'

a result, any tendency of the stream to dodge the zones by attempting to pass through the structure is superior meeting faces of theslow as to permit the gases to freely follow the spiral spaces, the action will be somewhat similar to that provided by the arrange ment of Fig. 3. Where, however, the rate of flow is increased so that the gases must traverse the field in a time length less than that which would be required to pass when following the spiral spaces, the gases will 'be forced to intersect the zones, the degree'of angularity at which such intersection takes place increasing with the increase in the rate of flow of the gases. Hence, the structure lends itself particularly tothe type of apparatus in which the gases are moved at considerable rapidity, the fact thatthe length of the field is not limited by thefactor of rigidity in the dis- In thislatter respect, the to that of the flexible wire structures, structures in which the vibratory effect and its disadvantages rapidly increase with the increase in length of the wire.

I have found,that a twisted bar of this character is particularl advantageous where the streams are forme of gases of comparcharge electrode;

atively high temperatures, the expansion action produced b the temperature of the gases tendingto e ongate the bar, the elongation, however, being wltha tendency to untwist to a more or less extent, depending upon the temperature. ing tendency may slightly affect the path of the spiral edges, the effect is comparatively small, thus retaining the action of the spiral zones, the untwisting action, how: ever, possessing tically retaining especially in view of While this untwistthe great advantageof prac the length of the radial ga between an edge and the outer electro e' constant. As a result, the

substantially bar provided by this expanchange in the vsi'on action ls'inefi'ective to materially change the character of the ionization zone proided by the edge; if any change be present, it'will simply be in a slight shifting of the zone itself tendinv .to straighten out the spiral. Consequently, an electrode system of this .form can be employed where the gases vary considerably as to temperature, expansion and contraction of y no material effect on the ionization zone itself.

Obviously, gular cross sectional contours, thus enabling the formation of any desirable spiral arrangement.- An additional advantage in the bar having the bar may have other anreadily understood, a discharge electrode such as described, will. where the radial distance between an edge and the outer eleca trode remains constant. throughout the length of the edge, even though the edge be in spiral form, produce a zone which will be continuous throughout the length of the edge, a result which is obtainable by the use of a tubular outer electrode, circular in cross section, with the axis of the discharge electrode on the symmetrical axis of the tube. If, however, the tube be non-circular in contour, the ionization zone will be interrupted in the direction of its length, since the radial length of the zone will vary, and, in accordance with the usual effect under such conditions, the strain lines will be con-' centrated more particularly at the points where such radial length is least.

As will be understood, the pitch of the spiral edges may be arranged to meet the conditions of service. It may be such that adjacent convolutions are close together, but

in such case I maychange the spiral arrangement to that of circular ribs, this being an arrangement more easily produced by machining, the spaces, in such case, extending circularly instead of spirally. In

such arrangement, the outer electrode is con-.

centric with the discharge edge to form a complete circular zone with the spaces independent of each other. Obviously, the stream, in this form, intersects the direction of length of the zones at direct right angles.

This latter idea can be applied under conditions of high temperature by employing a structure in which the effect of expansion and contraction does not materially vary the radial distance of the gap. A preferred way of producing such construction-is to form each rib as a unit, as indicated, for instance, in Fig. 12, in which m indicates a tubular member of suitable length formed \Qwith an external rib m, preferably wedgeshaped and having its periphery brought to a blunt edge. The "unit is adapted 'to Slip over and fit a carrier whicliirnay be either in bar or tubular form, of anyf desired cross-sectional configuration. Each member m is preferably of similar configuration, although this may vary, if desired. Obviously, a plurality of units can be placed on a single carrier, the latter being connected to the source of electrical sup ply, each unit being adapted to produce an independent zone when the carrier is mounted in a complemental electrode. The units may be clamped in position in suitable manner, preferably in a way which will peran edge, preferably mitremoval individually, if desired, or they the electrode is of the entire series, the weight of the units retaining them in position. The expansion and contraction effect will be more or less individual on the units, in addition to which desired strength and in a form which permits of easy manufacture and repair, and provides for uniformity in zones, in addition to which, any desired spacing of zones can be provided.

Obviously, a unit may'have more than a single rib, and may, if desired, include all of the ribs, in which case, the arrangement permits substitution of the edges of a discharge electrode without disturbing the conncction of the carrier with its spider support.

As will be readily understood, the ionization field produced when the arrangement of Fig. 12 above described is employed differs to some extent from the spiral form, in that each zone is symmetrically continuous on a cross sectional plane of the tubular or collecting electrode corresponding in position to the position of that portion of the discharge electrode which produces the zone. In other words, the zone intersects the direction of flow of the gases at direct right angles and is symmetrically continuous on the line of intersection, so that the gases are forced to pass through the successive spacedapart zones in traversing the field.

By these developments, I am able to provide a discharge electrode of sufiicient cross sectional area as will insure stability even though it be supported from one end only. For instance, I have employed electrodes of this type diameter, a construction which affords stability under exacting operating conditions, the outer electrodes being in the form of tubes in excess of fifteen inches in diameter. 1

In addition to providing for stability as a discharge electrode, the bar may itself form a supporting element, thus aiding in producing a more eflicient apparatus as a whole, in that such bars can operate tosupport the separating electrodes and additionally act in connection with tubular members to reduce the possibility of dust partic'les collecting on the insulators which support the system. In such cases, the radial length ofthe additional or supplemental zones is preferably greater than that of-the main or separating zones to reduce liability of disruptive discharge in such supplemental zones and thus affect the entire system.

I have found that the twisted bar isnot only very eificient in operation, but it additionally presents a structure of eat strength and integrity, due to the fact that the bar itself may be produced by the usual duced by the twisting action, thus retaining all of the metal of the bar and its general composition in the completed bar. v

As will be readily understood, the general idea may be employed in various Ways, dependent upon the capacity which the installation' is to provide, the drawings indicating several ways in which this result .may be obtained.

The structure 1s designed for use in connection with electrical currents of high potential. These may be of the alternating or the direct current type, and may be oscillating or pulsating in character.

In Fig. 5 I have shown a diagrammatic arrangement of parts where a rectified alternating current the tubular outer electrode connected to ground, 11 a twisted bar electrode suspended therein,'the bar being connected up to a rectifier 12 of suitable type operating to rectify the product of a transformer 13, the

arrangement providing a more quently, ifgases or other fluids be intro-- duced at the lower end of the tube at a predetermlned velocity, these gases will pass upwardly through the tube and intersect these ionization zones, the angle of intersection depending upon the pitch of the splral and the velocity of the gases, thus insuring that all portions of the gas will pass through one or more of these zones in reaching the opposite end of thetube'.

However, I prefer to employ the unidirectional type of current such as is provided by generators of the Girvin type, this typeof apparatus providing a unidirectlonal electromotive force of sufliciently high voltage with a minimum fluctuation between maximum and minimum vales, avoiding the more or less intermittent operation of the general type of rectifying apparatus. type of apparatus is unidirectional, the polarity of the bar remains the same and the electric intensity remains practically constant at all times, such'fluctuations that may exist being within well defined limits; hence there is no intermittance of the electric discharge from the active electrode provided the voltage 4 is kept above the corona-forming value.

In Figs. 6-10 I have shown various ways in which a bar may be employed in operat- 1s employed, 10 indicatingv27, the tubes 22 As the e. m. f. developed by this 'further eliminate the particles.

ing upon gases of comparatively high temperatures, such for instance, aswaste gases from blast furnaces.

In Fig. 6 I have shown a vertically extending tubular casing provided at its top with an insulator 15 by means of which the lead from the source of supply enters the casing the latter being indicated at 14. Arranged nearthe top of the casing is a suitable diaphragm 16 forming a support for post insulators 17,

insulator chamber, said insulators supporting a spider 18 from which depend a suit-' able number of bars 19, the lower ends of which are connected to a spider 20 which forms the support for the discharge electrode bars 2'1, said bars extending into the tubular electrodes 22 supported by a diaphragm or other support 23. i

The diaphragm 16 is provided with tubular sleeves 24 through which bars 19 extend, said sleeves having an inner diameter such as to provide a radial distance between a sleeve and it's rod 19 greater than the distance between a bar 21 and its tube 22, each rod or bar 19 being preferably formed with spirals to produce spiral ionization zones within the sleeve, although these bars may obviously be smooth. Suitable baffles 25 are located above the sleeves 24-. V Diaphragm 23, in this form, preferably has a central down-turned portion providing an opening, the lower end of said portion being connected to an, out-going pipe having their upper ends extending above the plane of diaphragm 23. 28 indicates the incoming pipe for the gases, this preferably having its outlet projecting downwardly within the casing 14.

In this form of device, a plurality of tubes 22 and a corresponding number of bars 21 are provided, these being arranged in a circle about the pipe 27. When gases are introduced through pipe 28 into the casing 1 1, with a definite velocity, the only escape from the casing is upwardly through the, tubes 22 which form part of the electrode system, having the spirally arranged ionization zones heretofore referred to. The gases after emerging from the tubes 22 pass into the chamber between diaphragms 16 and 23, from which they pass outward through pipe 27 Should the action of the electrode systems be insufiicient to thoroughlyclean the gases and there be a tendency of the latter to pass .upwardl-y'through the sleeves of diaphragm 16, the secondaryelectrode system provided by the bars or rods 19 and the sleeves would subject the gases to the action of such secondary ionization zones, thus tending to still As the gases would be required to follow a tortuous path in. entering the insulator chamber,

the chamber above said diaphragm being intended primarily as an ties, the tendency to deposit on the insulators -is.practically eliminated.

As a result, not only are the gases subjected to the main electrode systems, but such gases as mightreach the insulator chamber are subjectedto the action of the supplemental or secondary ionization fields and are required to traverse tortuous channels in reaching such chamber. Consequently, the deposit of dust within the insulator chamber is greatly reduced, if not entirely eliminated.

From the above. it will be seen that a structure is provided in which the discharge electrode system comprises supporting bars which may themselves act as secondary discharge electrodesand the bars 21, toget-her with their connections. Since the bars are of ample cross section (bars 19, in a commercial embodiment based on the disclosure of Fig. 6, having a diameter of four inches and bars 21 a diameter of approximately two inches), it will be readily understood that the structure thus produced is rigid and of a character able to withstand the usage to which it is to be put, the radial length of the ionization zone of the main system being approximately six inches while that of the secondary mately eight inches.

In Fig. 7 I have shown a. somewhat similar arrangement but of larger capacity, the main electrode system having its tubes arranged in concentric circles, the sp der being properly arranged to support the bars 21 with respect to the tubes 22,'thus greatly increasing the number of tubes 22 which may be employed. For instance, the structure shown in this viewds designed to employ about one hundred and fifty tubes 22, this structure being designed to provide a capacity in excem of one hundred thousand cubic feet of gas per minute at a comparatively low velocity. 7

Obviously. the general arrangement may be varied, Fig. 8 indicating one way in which this result may be obtained, this view indicating the possibility of tying the lower ends of bars 21 together by a spider.

'Fig. 9 indicates another application, this structure providing for an upward discharge of the gases, after separation, instead of downwardly as in the previous views, the insulator chamber in this instance being supplemental to casing 14 and provided in the form of an annular structure surrounding the outlet, the supporting bars 19 extending downwardly through openings in the casing 14. As will be readily understood, this particular arrangement permits systems is approxithe diaphragm or header 23 to extend entirely across the casing;

In Fig. 10' I have shown another form, spider 20 carrying the depending electrodes through the presence of the shields or batreadily understood that such particles as I may be separated will pass downward along these walls and through the space between tubes 22 and 50, passing into suitable pockets, which .inay have suitable controlled discharge outiets 100, the tubes 50 being supported in suitable manner, such support, if desired, forming the bottom of the pockets.

In this form, the supplemental separating zone is also employed. 7 If desirable, suitable screen or arrester structures may be provided in the lower portion of the casing, these structures being suitably supported and, in the types herein disclosed, face the discharge end of the gas inlet 28, being spaced therefrom a desired distance. This screen structure is designed more particularly to eliminate the larger particles which may enter with the gas, the latter discharging into the screen, and since the direction of flow of such gases within the casing is reversed in' reaching the separating fields, the screen structure will tend to prevent the larger particles from being retained'within the gas streams when reversing action is had.

It is characteristic of-the forms shown in Figs. 6-10 that the discharge electrodes are practically suspended or supported from their upper ends, although in Fig. 8, I have shown the lower ends of the electrodes as tied together. supporting these electrodes is not compulsory, Fig. 11 indicating a reversal in that the bars forming the discharge electrodes are supported from a spider located in the casing below the tubes 22. In this form, V

the spider is supported by rods 66 leading .downwardly from the insulator chamber through suitable pipes 70 external of the main casing, suitable deflectorsG'T being positioned below said pipes 70 and may be formed to catch particles which may be separated through the action of the supplemens tal ionization fields formed by the rods or bars 66 and the tubular members 70. These deflectors tend to force the gases toward the main separating fields and away from the supplemental fields. The tendency to prevent the passage of gases into the supplemental fields is additionally reduced through the fact that these fields and the insulator chamber tend to form a dead space, being out of the general circulation paths through the apparatus. In this form, the top of the casing may have a configuration tending to direct the gases which lead from the main separating fields towards the gas exit 27.

In each of these forms, the gas is introduced below the main separating fields and passes upwardly through these fields and thence to the exit, the suplemental separating fields'being designed to restrict, a'sfar as possible, the entrance of dust particles vinto the insulator chamber, it being understood that it is desirable that such chamber be kept from damaging effects as far as possible while providing-the support and circuit connections for the discharge elec-,

trodes.

It will be noticed that in these various forms, the structure is not only one involving stability, but that such'stability is obtained with a minimum amount of material and arranged in a comparatively compact member.v

These various arrangements indicate the wide possibilities of unit structure to meet various conditions of installation and of capacity, these generally employing the basic ideas relative to the formation'ot the ionization fields pointed out herein; While I have shown these various forms, it will be obvious that other variations or modifications embodying the general ideas may be provided to meet exigencies of use, and I therefore desire to be understood as reserving the right to make any and all such changes and variations as may be found necessary or desirable in so far as the same may fall within the spirit and scope of the invention as expressed in the accompanying claims.

In the following claims, it is to be understood that the discharge'electrode may be of either of the forms shown and described, excepting where a particular form is indicated. I

What I claim is 1. In the art of producing electrical precipitation from fluid or gaseous streams,

I the combination of opposing electrode systerns with the discharge system including a rigid electrode of angular cross-section, said electrode having a plurality of spiral dis-,

charge edges and said discharge edges being continuous. in length.

2. In the art of producing electrical precipitation of particles from fluid or gaseous streams, the combination of a plurality of tubular collecting electrodes, a rigid discharge electrode of angular cross-section extending axially Within each tubular electrode and havin a spiral discharge edge, said discharge .edge being in a plane concentric with the inner surface of its tubular electrode, means for introducing a stream into one end of each tubular electrode, and means for receiving and collecting the treated streams at the other'end of said tubular electrodes. I

3. In the art of producing electrical precipitation of particles from fluid or gaseous streams, the combination of a plurality of tubular collecting electrodes, a rigid discharge electrode of angular cross-section ex- 1 tending axially within each tubular elec-- trode and having a spiral discharge edge, said edge being in a plane concentric with the inner surface of its tubular electrode, means for introducing a stream into one endof eachtubular electrode, means for receiving and consolidating the treated streams at the other end of said tubular electrodes, and

means adjacent to one end of said tubular concentric with the'inner surface of its tubular electrode, means for introducing a stream into one, end of each tubular electrode, means for receiving and consolidating the treated streams at the other end of said tubular electrodes, and means adjacent to one end of the tubular electrodes 'for segregating the precipitated particles in said streams,

5. In the art of producing electrical precipitation of particles from fluid or gaseous streams and in combination, a plurality of suspended tlb'ular electrodes, a corresponding number of discharge electrodes extend ing axially within the tubular electrodes, means for suspending the discharge electrodes, said. means including a bar connected electrically to the discharge electrodes, a tubular member adapted to co-operate with said bar to produce an ionization field of less intensity than the fields produced by the discharge electrodes, and means for passing a streamthrough the ionization fields produced by the discharge electrodessaid supporting bar ionization field supplementing the action of the main ionization fields With respect to stream contents passing through the supplemental field.

6. In the art of producing electrical precipitation of particlesfrom fluid or gaseous streams and in combination, a casing, opposing electrode systems Within said casing, one of said systems including a plurality of discharge producing electrodes, aninsulator chamber within said casing, means for supporting the discharge electrodes from the insulator chamber, said means including ele ments adapted to produce ionization fields of less intensit than the fields produced by said electro e systems, and also includ- "ing'bamesto provide atortuous path for stream contents in reachin such chamber,

whereby said chamber 'w be protected gainst deposits by said supplemental ionization fields, and means for pas through the main ionization fiel -7. the art of producing electrical prefcipitation of particles -from fluid or gaseous "streams and in combination, a, casing, op- '10.

posing electrode systems within said cas- -mg, one of said systems including a pluralof discharge producing electrodes, an in ,sulator chamber within said casin means It ms bemg 'tion field for diverting] for supporting the discharge -e ectrod'es o 15' eluding elements adapted to produce ioniza- -,tion fields of less intensity than the fields from the insulator chamber, said means l1 l-' produced b said systems whereby said chamber wiiil be protected against deposits said supplemental ionization fields, and

a stream through the seous streams, opposing electrode systems mclud mg a collectifi electrode structure, said sys particles from the stream. and collecting t em in proximity to the collectinelectrode, and means in apv proximate i ent with the electrode I istructure for isolating the collected pars I ticles from the 1 j9;1In the m t eeting electricai pie astream;

.tems being pted .to produce an ioniz a in presence 0 two: witnesses.

cipita'tion of particles from fluid or gaseous streams, the combination of oppos' dg'uelectrode systems, said systems inclu g a plurality of tubular collectin electrodes, a.

rigid discharge electrode wit .each collecting electrode, means at one end of the tubular electrodes for supplying a stream solidating the streams emerging from said tubular electrodes, and means adjacent to one end of the electrodes for trapping the .to each tubular electrode, meansfor conparticles collected within saidtubular electrode and separating the particles from the outgoing streams.

10. In the art of producing electrical precipitationofparticles from fluid or aseous streams, 'oppo electrode systems mcluding a collectinge ectrode structure, said sysadapted to produce an ionization field'for iverting particles from-the stream and'collecting them in proximity to the sur- I face of-thecollecting electrode, said collectingelectrode being made in sections and the contiguous ends of said sections for a trap on the surface ofthe collecting e eetrode for isolating the collected particles from the stream.

ARTM w: i NESBIT. I

I H stain ,EDWARD'MG- -Ii1 testimon whereofll afix signature I 

